How this reference handles accuracy
Automotive DTCs are structured data, but diagnosis is vehicle-specific. This site distinguishes what can be stated generically from what must be verified against the exact vehicle.
Standards basis
SAE J2012 defines standardized Diagnostic Trouble Codes and identifies ranges reserved for manufacturer-specific use. SAE’s J2012 Digital Annex is the maintained data set for DTC definitions. The site uses that distinction to prevent P1xxx codes from being presented as universal definitions.
Generic versus manufacturer-specific
Standardized generic records: this site publishes and indexes a DTC only when the record is supported as a generic definition in the maintained reference data. The current library is primarily P0xxx and includes a small number of supported P2xxx records.
P1xxx records in this library: these are treated as manufacturer-specific. The same number may represent different faults by manufacturer, so the pages provide identification guidance instead of pretending one universal definition applies.
Diagnosis philosophy
The code identifies the condition the control module detected. Diagnostic content therefore focuses on preserving freeze-frame data, checking related codes, comparing commanded and actual scan data, inspecting circuits and mechanical conditions, and using the OEM test procedure before component replacement.
Why repair-cost ranges were removed
Repair cost depends on vehicle, labor market, access, diagnosis, parts quality, and whether the code is a symptom of another fault. A broad dollar range can be more misleading than useful before diagnosis, so the site no longer presents generic cost estimates as if they predict the required repair.
Primary references
- SAE J2012 — Diagnostic Trouble Code Definitions
- SAE J2012DA — Digital Annex (July 2026 revision)
- U.S. EPA OBD inspection/diagnostic guidance
- Vehicle-manufacturer service information and NHTSA-posted manufacturer technical service bulletins for vehicle-specific applicability.
Safety boundary
High-voltage systems, fuel under high pressure, internal transmission work, SRS/airbag systems, immobilizer/programming operations, and procedures requiring special tools or lifting/support equipment should be handled according to manufacturer procedures by appropriately trained personnel.